Portable white noise machine



FIG. 1 is a perspective view of a portable white noise machine showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines shown in FIGS. 3 and 7 illustrate portions of the portable white noise machine that form no part of the claimed design. 

CLAIM The ornamental design for a portable white noise machine, as shown and described. 